Running a DCC Equipped Loco in DC

mrgstrain · September 28, 2011, 7:25am

All this make’s me want to know. What is the advantage or maybe what is the pupose of disableing analog mode?

Is there any problem running them with analog mode inabled?

Larry

maxman · September 28, 2011, 7:55am

I’m not sure of the exact technical explanation, but as I understand it there is a DC component to the DCC signal (or something that looks like DC to the decoder). And when the track (or the loco) is first fired up, that DC component gets to the loco first. And when this happens the decoder thinks it is seeing DC and the unit will run away out of control. I don’t know if this is a problem with the current breed of decoders, but it used to be a problem with earlier decoders. Anyway, to prevent this from happening, the advice was to disable the analog mode.

I’m sure someone can chime in with a more correct technical explanation if I have any of the details wrong.

rrinker · September 28, 2011, 8:10pm

If the track power comes up before a stable signal is generated from the command station, a decoder set to allow analog conversion MIGHT see that as DC, and all that really does in the decoder is turn on the motor drivers, so the track power goes right to the motor, minus a little bit for the drop inside the driver electronics. In such a situation, the loco can suddenly take off in one direction or another.

–Randy

richg1998 · September 28, 2011, 8:44pm

The below link might shed some light.

http://www.wiringfordcc.com/runaway.htm

Be advised, a motor never sees direct track voltage from a decoder. The motor sees what the micro processor sends to it via the motor drivers. Either positive or negative going pulses, PWM. The track voltage goes right to the micro processor first. If the processor gets confused, it might not pick out the correct program from the ROM on the decoder.

The track voltage also goes to the bridge rectifier to develop the DC voltage operate the decoder.

Rich

joe323 · October 6, 2011, 3:23pm

What is the advantage of disabling DC in a dual mode decorder?

richg1998 · October 6, 2011, 4:10pm

Read though some of the responses. It has been mentioned.

Rich

BroadwayLion · October 7, 2011, 1:51pm

Doug from Michigan:

What am I missing here? I thought there were dire consequences for decoders if they ran in DC. Just when I thought I was understanding things, this one throws me for a loop.

Doug, as the OP of this thread, I would have thought the same thing at one time.

My first hint that a DCC equipped loco could be run on DC is the fact that in programming the decoder, the question is asked whether to set the decoder for DC operation.

I am thinking of selling some of my DCC equipped locos on eBay, and it crossed my mind that DC users might be interested in purchasing one or more of these locos. So, I began to wonder if the decoder could be reset to DC so that i wouldn’t have to remove the decoders before sale. In my mind, a DC guy who purchases such a loco has the advantage of being able to reset the decoder once again to DCC if he decides to go in that direction later on. Of course, the disadvantage of the decoder to the DC user is that he is paying for something that he doesn’t need. My problem is that I am stuck with an used decoder if I sell the loco without it.

Rich

If you sell your DCC loco to a DC guy, he will NOT be able to change it back himself, because he has no DCC gear that will do this for him. Well, ok, I can do it: I open up the loco, remove the offending electronics and wire it my way.

rrinker · October 7, 2011, 8:34pm

If it’s a plug-in decoder or you otherwise didn;t cut wires or modify it, you can sell the decoder too. Probably get more by sellign them seperately as well. On the other hand, plenty of people would like a loco they can just take out of the box and put on the track, without having to install a decoder.

–Randy